Project Summary/Abstract Rates of opioid prescribing and opioid-related overdose deaths have quadrupled in the United States over the past 25 years. This epidemic has increasingly affected older adults, among whom hospitalization rates for opioid overdoses grew five-fold from 1993-2012. Risks of opioid use are particularly pronounced for older adults, who are vulnerable to opioids? side effects. Although substantial attention has been placed on inappropriate prescribing of opioids, the ways in which opioid-nave patients develop long-term opioid use are mostly unknown. One of the most common settings for older adults to receive opioids is after surgery. The period after surgery is a particularly vulnerable one for opioid use, both because of older adults? clinical fragility after surgery and because the post-hospitalization period often involves a highly fragmented transition of care. However, little data exist on the extent to which opioids are prescribed following surgery among older adults, surgeries for which prescribing and opioid-related adverse events are most common, and the role of surgeon- and hospital-level factors in contributing to short- and long-term prescription opioid use. Many argue that variation in physician prescribing behavior has been a driver of the opioid epidemic. However, no research has explored the extent to which individual surgeons vary in opioid prescribing following surgery and the implications of that variation for patients? long-term opioid use and related adverse outcomes. In addition, little research has examined whether intra- and post-operative pain management techniques such as regional anesthesia, which may reduce pain following surgery, may also reduce long-term opioid use and related adverse outcomes after surgery. The proposed research will quantify the short- and long-term effects of opioid prescribing following surgery ? including short-term opioid-related adverse events and the transition to long-term use ? among previously opioid-nave older adults who undergo inpatient surgery using Medicare administrative claims. Because a key challenge in identifying the effect of surgeons in contributing to short- and long-term opioid use after hospitalization is separating the effects of provider practice patterns from unobservable patient characteristics that affect opioid use, the proposed research will develop novel quasi-experimental approaches that rely on quasi-random assignment of hospitalized Medicare beneficiaries to providers of varying opioid-prescribing intensity. The proposed research will also develop quasi-experimental methods to study how different approaches to pain management during surgery (use of regional anesthesia) influence post-operative opioid use and potentially downstream opioid-related adverse outcomes. Results from this research will help define the risks of post-operative opioid use among older adults and can inform the need, design and potential impact of policies that target providers to improve the appropriateness of post-surgical opioid prescribing among older adults.